i just changed out the thermostat on my 4.0 and everything went pretty smooth. i got new sensors as well as a new thermostat. problem is the temp guage keeps going up. it used to idle around 176 and now its getting near 200 and going up just idling. i used new coolant, distilled water and 50/50 mix. im not leaking coolant either. could i have put in too much coolant?

 

sounds to me that you have an air bubble in the system...pop the rad cap off and let the engine idle for a little and rev the engine to around 2k a few times...also turn the heater on full blast

 

ok heaters on full blast, it took a little to heat up, the rad cap is off too(should i do reserve top off too?) i reved it a few times. is it normal for a little coolant to leak out of the top of the rad when tops off? should i keep refilling?

what idle temp should i be happy with? 192?

 

it will bubble out a little bit...and when mine is idleing and warmed up the temp is around 195

 

ok cool, idling its staying about there. once it bubbles out should i refill or no? when i drive it fluctuates a bit is that normal? before it would be around 176-183 religiously so should i expect about 10 degree fluctuation while driving?

 

heres what you do...after its warmed up with the cap off...shut the truck off, leave the cap of for a while(air will gradually make its way out) AKA the engine "burping' and then top the rad/overflow tank off

 

sweet thanks man appreciate the fast help.

 

Ok well everything is running perfectly fine from the looks of things, but i had one question. I looked at my stock thermo that i changed out, and it had the same marking on it as the new one, it showed engraved in the metal 92-106 degrees celcius. that translates to 197.5-225 or so. why is it that my truck was running 20 degrees cooler on this thermo versus the new, without there being any cooling issues.

 

not following you...

 

the thermo i took out of truck, was rated the same exact temp as the new stock one i bought, but before this new thermo, the old one(stock) ran at 20 degrees cooler than this exact same thermostat, my question is why is that?

 

Old one was probably stuck open a little bit.

 

i changed my thermostat two weeks ago and installed an electric fan and now im still having the same problem. truck ran great for a week, went wheeling and beat the **** out of it, now just going down the highway it starts to overheat??? any ideas

 

ya its prob ur electric fan not pulling enough air. i dont understand why ppl go with elec fans....i have never heard of a car with a mechanical fan overheating, they are just so failsafe.....i could be wrong tho about your problem specifically

 

i had no fan at all for over a year. never had any problems before, now all of a sudden it is over heating.

the reason people go with electric fans is to reduce the load on the engine, less spinning weight and less power lost to turning it. helps with power and fuel economy. although i only put it on cause my mechanical fan broke

 

fair enough, but imo, i dont think its necessary unless its a sports car or something with some decent power. for stock levels or anything near, i just dont see enough of a positive to do the work/money/fab. but hey more power to you fellow modder!

 

The fan does nothing over 30, at idle the electric out performs the mech, and when the clutch goes bad its cheaper to get an electric.

Best reason ever is colder AC at a stop.


Over heating on the highway is a capacity issue. Meaning you don't have enough cooling capacity. I suggest a full flush and leak check.

 

It should stay around 200 give or take 10 degrees

 

what i dont get is it is totally intermittent. i can go wheeling all day and flog the crap out of it with no issues. two days later it is overheating like a bastard under normal driving